The invention relates to a mixer with a fixed drum. It will be used for achieving thorough mixing of dry or wet constituents, such as, for example, for the manufacture of concrete, refractory products, silica sand and the like.
Mixers comprise a generally circular drum in which the various constituents of the mixture are placed and a mixing arrangement which is composed of movable blades, generally set in rotation, these blades promote thorough mixing of the constituents, the entire mixing arrangement being moved in the drum in order to homogenize the entire mixed product.
There are two major categories of mixer; mixers comprising a rotary drum in which the position of the mixing arrangement is fixed, on the other hand, the drum carries out a rotary movement which entrains the product and periodically subjects it to the action of the mixing arrangement. Thus it is possible to homogenize the entire mixed product, however it should be noted, in this type of mixer, that the heaviest and bulkiest part of the machine is set in rotation.
Then there are mixers with a fixed drum, in which the drum containing the product is fixed whereas the mixing arrangement, apart from its rotary movement about its own axis, is rotated in the drum, which causes the blades to describe an epicyclic movement, which makes it possible to move all the product located in the drum and thus to homogenize it. The entire device for driving the mixing arrangement is located in a rotary casing of large dimensions, in view of the forces introduced and consequently this type of mixer is particularly suitable for manufacture in large numbers in view of the fact that the least modification in the dimensions of the gears makes it necessary to revise the shape of the casing, which cannot be envisaged reasonably if one wishes to obtain a relatively low final cost price. Apart from the fact that it cannot be easily adapted to different conditions of use, the mixer comprising a fixed drum also has the drawback that the upper part of the drum is not easily accessible when it is in operation, since it is perpetually swept by the moving mixing arrangement and the central part of the drum is occupied by the drive member which actuates the mixing arrangement by means of its driving device. Consequently, it cannot be envisaged, for example, to add to the mixing arrangement any tool such as a motorized mixing screw which would be fitted in the drum as an accessory in order to perfect mixing.